Altostratus Amount-When-Present (%) December, January, February (1954 - 1997) Night, Ship Observations Only Global Average: 61.6 Zonal Averages 17 zones Lat.N Average 85 90.0 75 61.8 65 76.4 55 70.5 45 64.7 35 63.1 25 55.1 15 47.3 5 57.0 -5 63.1 -15 57.5 -25 56.6 -35 58.8 -45 59.4 -55 79.3 -65 82.6 -75 73.7 Grid Box Averages 278 filled boxes Box # Lat.N Lon.E Average 2 85 180 90.0 4 75 20 65.2 5 75 60 58.5 13 65 10 72.0 21 65 170 70.0 29 65 330 84.6 30 65 350 72.4 31 55 10 72.8 32 55 30 67.7 38 55 150 63.4 39 55 170 57.6 40 55 190 64.0 41 55 210 66.5 42 55 230 66.0 46 55 310 82.3 47 55 330 80.7 48 55 350 77.7 49 45 5 59.8 50 45 15 68.1 52 45 35 60.9 62 45 135 55.7 63 45 145 53.9 64 45 155 52.8 65 45 165 52.0 66 45 175 55.9 67 45 185 60.2 68 45 195 54.5 69 45 205 58.0 70 45 215 62.7 71 45 225 67.5 72 45 235 67.6 77 45 285 76.4 78 45 295 80.2 79 45 305 80.2 80 45 315 81.3 81 45 325 76.2 82 45 335 75.0 83 45 345 74.2 84 45 355 72.3 85 35 5 58.5 86 35 15 58.2 87 35 25 59.9 88 35 35 57.8 97 35 125 70.5 98 35 135 62.3 99 35 145 57.5 100 35 155 55.0 101 35 165 60.7 102 35 175 58.5 103 35 185 57.3 104 35 195 58.0 105 35 205 63.6 106 35 215 62.6 107 35 225 64.0 108 35 235 59.7 109 35 245 56.5 112 35 275 56.9 113 35 285 71.2 114 35 295 74.5 115 35 305 69.0 116 35 315 70.7 117 35 325 68.1 118 35 335 65.2 119 35 345 63.5 120 35 355 60.5 124 25 35 46.0 126 25 55 53.7 127 25 65 38.3 132 25 115 66.8 133 25 125 61.3 134 25 135 51.0 135 25 145 45.6 136 25 155 50.6 137 25 165 49.5 138 25 175 49.7 139 25 185 50.0 140 25 195 52.3 141 25 205 58.5 142 25 215 61.0 143 25 225 65.1 144 25 235 60.8 145 25 245 59.5 146 25 255 60.7 147 25 265 64.9 148 25 275 48.2 149 25 285 50.0 150 25 295 49.8 151 25 305 53.1 152 25 315 54.4 153 25 325 49.3 154 25 335 58.0 155 25 345 58.7 160 15 35 43.0 161 15 45 41.4 162 15 55 35.5 163 15 65 30.5 164 15 75 39.9 165 15 85 37.1 166 15 95 27.7 167 15 105 61.2 168 15 115 43.3 169 15 125 47.4 170 15 135 48.9 171 15 145 38.4 172 15 155 40.6 173 15 165 43.5 174 15 175 39.4 175 15 185 43.1 176 15 195 52.5 177 15 205 50.5 178 15 215 49.0 179 15 225 60.3 180 15 235 65.0 181 15 245 57.8 182 15 255 48.8 183 15 265 34.3 184 15 275 39.2 185 15 285 39.5 186 15 295 33.6 187 15 305 41.3 188 15 315 46.1 189 15 325 54.5 190 15 335 65.8 191 15 345 63.8 193 5 5 62.9 198 5 55 41.5 199 5 65 46.8 200 5 75 52.0 201 5 85 56.9 202 5 95 56.0 203 5 105 60.5 204 5 115 54.4 205 5 125 53.9 206 5 135 59.2 207 5 145 53.4 208 5 155 57.4 212 5 195 63.4 219 5 265 54.7 220 5 275 49.6 221 5 285 50.1 223 5 305 43.8 224 5 315 54.4 225 5 325 69.1 226 5 335 65.2 227 5 345 62.2 228 5 355 59.0 229 -5 5 62.0 230 -5 15 44.9 233 -5 45 50.6 234 -5 55 57.4 235 -5 65 72.0 236 -5 75 64.0 237 -5 85 64.0 238 -5 95 69.1 239 -5 105 72.0 240 -5 115 72.0 241 -5 125 67.2 242 -5 135 72.9 243 -5 145 70.0 244 -5 155 58.5 247 -5 185 62.0 248 -5 195 64.0 255 -5 265 63.1 256 -5 275 60.3 260 -5 315 40.7 261 -5 325 46.0 262 -5 335 44.9 264 -5 355 54.6 265 -15 5 67.7 266 -15 15 50.2 269 -15 45 58.7 270 -15 55 62.0 271 -15 65 60.9 272 -15 75 59.9 273 -15 85 57.5 274 -15 95 56.0 275 -15 105 47.7 276 -15 115 44.0 277 -15 125 59.7 279 -15 145 67.3 280 -15 155 53.1 281 -15 165 51.2 282 -15 175 57.8 283 -15 185 71.9 284 -15 195 71.8 285 -15 205 65.6 286 -15 215 52.7 292 -15 275 52.9 293 -15 285 48.9 297 -15 325 47.8 299 -15 345 46.5 300 -15 355 58.9 301 -25 5 61.6 302 -25 15 49.7 304 -25 35 64.7 305 -25 45 59.6 306 -25 55 57.4 308 -25 75 48.7 310 -25 95 61.6 311 -25 105 50.3 312 -25 115 36.5 316 -25 155 57.7 317 -25 165 51.6 318 -25 175 58.3 319 -25 185 59.8 320 -25 195 66.6 322 -25 215 74.1 323 -25 225 62.6 328 -25 275 44.7 329 -25 285 54.9 332 -25 315 55.0 333 -25 325 52.5 336 -25 355 54.3 337 -35 5 56.1 338 -35 15 45.6 339 -35 25 53.7 340 -35 35 67.4 342 -35 55 62.9 343 -35 65 76.9 344 -35 75 64.6 345 -35 85 55.5 346 -35 95 59.5 347 -35 105 58.9 348 -35 115 50.3 349 -35 125 60.7 350 -35 135 67.8 351 -35 145 60.3 352 -35 155 63.7 353 -35 165 60.9 354 -35 175 60.3 355 -35 185 66.9 356 -35 195 60.8 357 -35 205 63.0 363 -35 265 56.0 364 -35 275 47.2 365 -35 285 37.8 367 -35 305 51.9 368 -35 315 56.0 371 -35 345 66.5 372 -35 355 54.8 380 -45 75 78.4 388 -45 155 63.4 389 -45 165 63.9 390 -45 175 60.8 391 -45 185 63.8 400 -45 275 52.7 401 -45 285 50.3 402 -45 295 43.5 403 -45 305 50.2 409 -55 10 87.7 410 -55 30 87.8 411 -55 50 80.6 412 -55 70 81.5 413 -55 90 92.7 415 -55 130 75.0 416 -55 150 77.2 417 -55 170 71.9 423 -55 290 64.3 424 -55 310 63.5 425 -55 330 68.1 426 -55 350 89.4 427 -65 10 79.1 428 -65 30 83.6 429 -65 50 74.7 430 -65 70 68.7 431 -65 90 84.7 432 -65 110 79.8 433 -65 130 84.8 434 -65 150 78.6 435 -65 170 81.3 436 -65 190 88.2 437 -65 210 91.5 438 -65 230 90.6 441 -65 290 79.2 442 -65 310 81.1 444 -65 350 81.8 449 -75 180 71.3 453 -75 340 79.7